Thermoelectric properties of layered perovskite-type (Sr1−xCax)3(Ti1−yNby)2O7

Publisher Website
Google Scholar
Abstract
The thermoelectric properties and crystallographic features of layered perovskite-type Ca-substituted ( Sr 1 − x Ca x ) 3 ( Ti 1 − y Nb y ) 2 O 7 ( y = 0 – 0.2 ) , Ruddlesden-Popper phases were investigated. The influence of crystal structure and carrier concentration on the carrier effective mass for Ti-based metal oxides based on TiO 6 octahedra and having a significant Ca substitution effect are discussed. It was found from structural analysis that the large Seebeck coefficients of Ca-substituted compounds can be attributed to the high values of carrier effective mass, which originates from the enhancement of the symmetry of the TiO 6 octahedra. Low thermal conductivities, 3.6 – 3.8 W m − 1 K − 1 at 300 K, were obtained for Ca-substituted compositions due to phonon scattering at SrO ∕ ( SrTiO 3 ) 2 interfaces of the inherent superlattice structure and to mass-defect phonon scattering between Ca ( M Ca = 40 ) and Sr ( M Sr = 88 ) . The highest Z T value obtained was 0.15 at 1000 K, for 10 at % Ca-substituted Sr 3 ( Ti 0.95 Nb 0.05 ) 2 O 7 .